Walgett's Drinking Water: Yuwaya Ngarra-li Briefing Paper

This Briefing Paper documents a timeline of events in Walgett's recent history of drinking water management. It sets out the context in which drinking water is accessed, the associated risks, and the story of community advocacy pivotal to change. Its purpose is to inform efforts to improve water security and quality for residents in Walgett and the nearby Namoi and Gingie Villages, including urgent actions called for by the Dharriwaa Eldergs Group and Walgett Aboriginal Medical Service

Construction of probabilistic event trees for eruption forecasting at Sinabung volcano, Indonesia 2013-14

Eruptions of Sinabung volcano, Indonesia have been ongoing since 2013. Since that time, the character of eruptions has changed, from phreatic to phreatomagmatic to magmatic explosive eruptions, and from production of a lava dome that collapsed to a subsequent thick lava flow that slowly ceased to be active, and later, to a new lava dome. As the eruption progressed, event trees were constructed to forecast eruptive behavior six times, with forecast windows that ranged from 2. weeks to 1. year: November 7-10, December 12-14, and December 27, 2013; and January 9-10, May 13, and October 7, 2014. These event trees were successful in helping to frame the forecast scenarios, to collate current monitoring information, and to document outstanding questions and unknowns. The highest probability forecasts closely matched outcomes of eruption size (including extrusion of the first dome), production of pyroclastic density currents, and pyroclastic density current runout distances. Events assigned low probabilities also occurred, including total collapse of the lava dome in January 2014 and production of a small blast pyroclastic density current in February 2014

Intrusión magmática asociada a la sismicidad distal en el volcán Sabancaya, 2020 – 2021

El volcán Sabancaya ha registrado entre el 2020 y 2021 una importante sismicidad volcano tectónica distal – VTD, la cual se ha manifestado en algunas ocasiones a modo de enjambres sísmicos. El registro de enjambres sísmicos VTD en ambientes volcánicos se asocia a la sobrepresurización de los acuíferos que cruzan las fallas tectónicas debido a la intrusión de magma, y en el volcán Sabancaya ha sido asociada a intrusiones importantes de magma provenientes de la cámara magmática localizada por debajo del volcán Hualca Hualca. La cual al migrar hacia el volcán muestra incrementos de sismicidad proximal asociada a la dinámica de fluidos y actividad explosiva y el registro de valores importantes de anomalías térmicas, que indicaría un mayor volumen de magma involucrado en el conducto del cráter, que conllevo a la formación domos exógenos y endógenos. La sismicidad desde el 2013 y aquella como parte del proceso eruptivo, sigue el modelo conceptual de 4 etapas de sismicidad de White y McCausland (2019) que precede a las erupciones en volcanes inactivos. Antes sus inicios en 2016, el proceso eruptivo sugiere un sistema más abierto, es por ello, que no ocurren todas las etapas, como es el caso del periodo comprendido entre el 2020 y 2021, en el cual el patrón sísmico muestra el registro de sismos VTDs debido a la intrusión de magma (Etapa 2) seguida por sismicidad proximal asociada a la migración de fluidos y gases hacia la superficie (Etapa 3) y el ascenso final del magma a modo de sismos acoplados (Etapa 4)

Cutting Costs by Locating High Production Wells: A Test of the Volcano seismic Approach to Finding ''Blind'' Resources

In the summer of 2000, Duke University and the Kenyan power generation company, KenGen, conducted a microearthquake monitoring experiment at Longonot volcano in Kenya. Longonot is one of several major late Quaternary trachyte volcanoes in the Kenya Rift. They study was aimed at developing seismic methods for locating buried hydrothermal areas in the Rift on the basis of their microearthquake activity and wave propagation effects. A comparison of microearthquake records from 4.5 Hz, 2 Hz, and broadband seismometers revealed strong high-frequency site and wave-propagation effects. The lower frequency seismometers were needed to detect and record individual phases. Two-dozen 3-component 2- Hz L22 seismographs and PASSCAL loggers were then distributed around Longonot. Recordings from this network located one seismically active area on Longonot's southwest flank. The events from this area were emergent, shallow (<3 km), small (M<1), and spatially restricted. Evidently, the hydrothermal system in this area is not currently very extensive or active. To establish the nature of the site effects, the data were analyzed using three spectral techniques that reduce source effects. The data were also compared to a simple forward model. The results show that, in certain frequency ranges, the technique of dividing the horizontal motion by the vertical motion (H/V) to remove the source fails because of non-uniform vertical amplification. Outside these frequencies, the three methods resolve the same, dominant, harmonic frequencies at a given site. In a few cases, the spectra can be fit with forward models containing low velocity surface layers. The analysis suggests that the emergent, low frequency character of the microearthquake signals is due to attenuation and scattering in the near surface ash deposits

Stress and mass changes at a "wet" volcano: Example during the 2011-2012 volcanic unrest at Kawah Ijen volcano (Indonesia)

Since 2010, Kawah Ijen volcano has been equipped with seismometers, and its extremely acid volcanic lake has been monitored using temperature and leveling sensors, providing unprecedented time resolution of multiparametric data for an acidic volcanic lake. The nature of stress and mass changes of the volcano is studied by combining seismic analyses and volcanic lake measurements that were made during the strongest unrest ever recorded by the seismic network at Kawah Ijen. The distal VT earthquake swarm that occurred in May 2011 was the precursor of volcanic unrest in October 2011 that caused an increase in shallow earthquakes. The proximal VT earthquakes opened pathways for fluids to ascend by increasing the permeability of the rock matrix. The following months were characterized by two periods of strong heat and mass discharge into the lake and by the initiation of monochromatic tremor (MT) activity when steam/gases interacted with shallow portions of the aquifer. Significant seismic velocity variations, concurrent with water level rises in which water contained a large amount of steam/gas, were associated with the crises, that caused an although the unrest did not affect the shallow hydrothermal system at a large scale. Whereas shallow VT earthquakes likely reflect a magmatic intrusion, MT and relative seismic velocity changes are clearly associated with shallow hydrothermal processes. These results will facilitate the forecast of future crises.SCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe

Recent explosive eruptions and volcano hazards at Soputan volcano-a basalt stratovolcano in north Sulawesi, Indonesia

Soputan is a high-alumina basalt stratovolcano located in the active North Sulawesi-Sangihe Islands magmatic arc. Although immediately adjacent to the still geothermally active Quaternary Tondono Caldera, Soputan\u27s magmas are geochemically distinct from those of the caldera and from other magmas in the arc. Unusual for a basalt volcano, Soputan produces summit lava domes and explosive eruptions with high-altitude ash plumes and pyroclastic flows-eight explosive eruptions during the period 2003-2011. Our field observations, remote sensing, gas emission, seismic, and petrologic analyses indicate that Soputan is an open-vent-type volcano that taps basalt magma derived from the arc-mantle wedge, accumulated and fractionated in a deep-crustal reservoir and transported slowly or staged at shallow levels prior to eruption. A combination of high phenocryst content, extensive microlite crystallization and separation of a gas phase at shallow levels results in a highly viscous basalt magma and explosive eruptive style. The open-vent structure and frequent eruptions indicate that Soputan will likely erupt again in the next decade, perhaps repeatedly. Explosive eruptions in the Volcano Explosivity Index (VEI) 2-3 range and lava dome growth are most probable, with a small chance of larger VEI 4 eruptions. A rapid ramp up in seismicity preceding the recent eruptions suggests that future eruptions may have no more than a few days of seismic warning. Risk to population in the region is currently greatest for villages located on the southern and western flanks of the volcano where flow deposits are directed by topography. In addition, Soputan\u27s explosive eruptions produce high-altitude ash clouds that pose a risk to air traffic in the region. © 2012 Springer-Verlag